1. Field of the Invention.
The present invention is directed to an efficient and cost effective apparatus and method of generating a high security optical variable device(OVD).
2. Description of the Prior Art.
In the optical process many applications are required to record an interference fringe where a wavefront is to be reconstructed. In general, a fringe pattern is recorded by interfering more than one wavefront beam and recording the fringe onto a high resolution photo-material. However, it is difficult to obtain a fringe pattern which is designed for special applications such as information processing, non-sphere wavefront, etc. For a high security application, it is necessary to record a well-designed pattern so that it is difficult or impossible to counterfeit.
In addition, holography has been a commercially viable product in the security and packaging fields for more than a decade. Landis & Gyr has developed an E-beam written "Kinegram", marketed with its brilliant optical diffractive appearance. CSIRO developed another E-beam OVD called "Pixelgram". Toppan Printing Co. has an E-beam OVD that includes dot-matrix type and 3D grating images. While E-beam generated OVD provides eye catching appearance, it's high cost has become price prohibitive. Very few entities, except government agencies, can afford it. Conventional holographic services have developed much more rapidly, mostly due to the fact that equipment costs are relatively affordable. The present invention was designed to alleviate the drawbacks of the prior art in an effort to provide affordable and high precision diffractive OVD and/or hologram services in a timely manor.
It is an object of the present invention to alleviate the drawbacks of the prior art and to provide an extremely low cost and an effective high speed fringe recording system and method of operating the same.
It is another object of the invention to provide a high speed recording process by using a Liquid Crystal Display (LCD). A computer generated pattern is displayed on the LCD. A collimated laser beam illuminates the LCD and the pattern is imaged onto a photo-material plane with a (X) reduction in size. The pattern displayed on the LCD is shifted in a constant speed. Meanwhile, the photo-material plane is shifted in the same speed so that the pattern can be recorded in extreme high speed.
It is yet an another object of the invention to provide a pattern recording process for the diffractive hologram from a computer generated pattern. A laser beam is focused onto a photo-material plane within a micron order size. The laser beam is switched on and off as to respond to the binary data which is transformed from a computer generated pattern. This recording process offers a very fine pattern forming a diffractive object.
This invention discloses an efficient and cost effective method of generating a high security optical variable device(OVD). Prior art electron beam devises generate a very detailed diffractive grating, but it is extremely costly, slow, and has restrictive ion size. Other conventional holographic systems used to produce various types of 2D and/or 3D images cost less, but have a restrictive performance. This invention provides a method that not only produces optical effect/images that E-Beam systems and conventional holographic systems can, but does it faster and is more cost effective.